The invention relates to a method of manufacturing a saddle-shaped deflection coil which flares out from a rear end towards a front end and is of the type having an arcuate connection portion at the front end, an arcuate connection portion at the rear end and two interposed coil flanks, said method comprising the steps of:
a. providing a jig having a recess formed between two jig sections, which recess has a shape which corresponds to the desired shape of the coil, for taking up continuously fed winding wire; and PA1 b. continuously feeding winding wire to the recess for forming a plurality of coil turns.
Winding saddle-shaped deflection coils, particularly saddle-shaped line deflection coils for use in picture display tubes, is a generally known technique. It is conventional practice to combine a set of saddle-shaped line deflection coils with a set of saddle-shaped field deflection coils or a set of field deflection coils toroidally wound on a core to form an electromagnetic deflection unit. The nominal design of the coils may be such that, for example, certain requirements with respect to the geometry of a raster scanned by means of the deflection unit on the display screen of a display tube and/or with respect to the convergence of the electron beams on the display screen are satisfied.
However, it has recently been found that in spite of a satisfactory nominal design certain combinations of deflection units and display tubes, particularly for use in colour monitors, sometimes exhibit a convergence error, the so-called line astigmatism whose magnitude differs from combination to combination.